Where is the choroid thickest?

Where is the choroid thickest?

• A. Posterior pole
• B. Ora serrata
• C. Equator
• D. Fovea

Answer: (A)

The choroid is thickest in the posterior pole because this region has the highest metabolic demand from the outer retina, especially beneath the macula and near the optic nerve. Its layers—large vessels in the deeper part and a dense choriocapillaris closer to the retina—provide the substantial blood supply needed to support the photoreceptors and RPE. As you move anteriorly toward the equator and then to the ora serrata, the demand and the vascular mass decrease, so the choroid becomes thinner. The fovea sits within the macula, but the choroid directly underneath is not the deepest part; the thickest portion is posteriorly, behind the central retina.

The choroid is thickest in the posterior pole because this region has the highest metabolic demand from the outer retina, especially beneath the macula and near the optic nerve. Its layers—large vessels in the deeper part and a dense choriocapillaris closer to the retina—provide the substantial blood supply needed to support the photoreceptors and RPE. As you move anteriorly toward the equator and then to the ora serrata, the demand and the vascular mass decrease, so the choroid becomes thinner. The fovea sits within the macula, but the choroid directly underneath is not the deepest part; the thickest portion is posteriorly, behind the central retina.